Elastic thread



May 25, 1948. s. w. ALDERFER 2,442,279

ELASTIC THREAD Original Filed July 1, 1944 2 Sheets-Sheet 1 QwumvbovTEQUNG w ALDERFER m fgl ma www@ Summa/lit' May 25, 1948. s. w. ALDERFERELASTIC THREAD Original Filed July l, 1944 2 Sheets-Sheet 2 SWW/who@515ml Na 'w ALDERFER Patented May 25, 1948 ELASTIC THREAD Sterling W.Alderier, Akron, Ohio l Original application July 1, 1944, Serial No.

543,132. Divided and this application June 28, 1945, Serial No. 601,577

4 Claims.

, l This invention relates to new and improved elastic thread, cords,cables orY the like and to fabrics made therefrom or incorporating suchelements. The products covered hereby have new and useful properties.

Heretofore it has been diiiicult to make an elastic fabric which iseasily stretchable or, as

it is termed in the trade, a lazy" fabric. Fabrics oi this type areespecially desirable in the manufacture of articles of apparel whichshould have (therefrom. Because of the substantial tension which isordinarily maintained, the finished fabric has a very strong tendency tocontract. The desired property of a mild tendency to contract, justsufficient to cause the garment to cling to the body without exertingexcessive constriction, is impossible or dimcult to obtain underexisting processes for the reasons stated.

One of the objects of the invention is to provide a lightly tensionedelastic thread or cord from which a garment or tape may be fabricated onstandard weaving, braiding or knitting machines without the diiiicultiesdue heretofore to the elongation of such a thread or cord. It is,therefore, possible by practicing the invention to secure a moderateelasticityin a finished thread or in a garment made on the ordinarycovering and knitting or weaving machines.

This application is a division of my prior copending application, SerialNo. 543,132, filed July 1, 1944, now Patent No. 2,427,334, datedSeptember 16, 1947. This patent is directed to the new processes formaking the elastic thread or fabric, while the present application isdirected to the completed products. In order to make the presentinvention clear and understandable it is deemed advisable to describeprocesses by which the products may be made, although it may beconceived that other processes might be devised to secure the resultantmaterials. It is therefore, not to be considered that the subject matterof the present application is necessarily confined to productsmanufactured by the processes herein described.

In the accompanying drawings and description, there are shown severalforms of the invention, and several methods which may be employed, butit will be understood that the invention is not limited to the specificmaterials, details or steps shown, for, when the principles areunderstood,

2 it is possible to devise modifications or improvements thereon withoutdeparting from the basic principles of the invention.

The products may be made by attaching or depositing the rubberconstituent of the thread upon a backing or foundation which has someability to elongate, but which will reach its maximum elongation at apoint where the rubber portion oi the composite material has reached thedetermined tension which will give desired elasticity to the finishedthread or garment. There is little or no recovery in a sheet of thismaterial after it has been stretched or orientedf so that the rubber isheld in tension by the backing material. As a, result, when thecomposite rubber and plastic thread is covered with any suitable textilematerial, the thread has no stretch or an easily controlled stretch.Also, when the threads are placed in the knitting or weaving machine,this property of the thread permits the machine to operate with the easeand at speeds which are obtained in the manufacture of non-elasticfabrics.

When the thread is covered, if an elastic thread is the finishedproduct, or when the fabric is completed,v the thread (or fabric) ispreferably put through a finishing bath to remove the dirt, oil orsizing which may be found thereon. Water soluble backing material willdissolve in the bath leaving a. soft, mildly elastic fabric or thread.While a water soluble backing is preferred because it is readilydestroyed in the usual nishing bath, any other fugitive backing may beemployed with an appropriate after treatment which will remove theplastic material but is non-deleterious to the rubber or coveringmaterial.

In some aspects of the invention it may be desired to use as the backingmaterial a non-fugitive plastic which has a certain amount of stretchand ability to move with the rubber element of the thread or cord. Abacking of this type will be retained in the finished thread or fabric,and while it will perform the same function of giving to the thread thefirmness which is so desirable for the covering and knitting or weavingoperations, it does not unduly aect the elasticity of the finishedproduct. An advantage of this form of the invention is that if therubber element should be cut or broken during the subsequentmanufacturing operatons, the rubber thread will not retract and lose itselastic properties as is a common fault in ordinary elastic fabrics, butwill be retained in position and, therefore, the elastic effect of thethread will be retained on either side of the break.

The composition of the backing sheet is determined by a number offactors.

readily water soluble. The backing material should have the ability tostretch or elongate and to reach its maximum elona'ation at the pointwhere the desired elongation or tensionupon the rubber is reached. Therehave been developed recently a number of plastics or synthetic resinswhich will answer these requirements, and while it is not wished orintended to limit the invention in any manner to one material or groupof materials. it has been folmd that polyvinyl alcohol and itsderivatives will operate satisfactorily.

For the rubber constituent of the thread it is preferred to employ anatural or artificial waterdispersion of rubber. Natural latex isadmirably. suited for the purpose as are the water-dispersions ofnatural or synthetic rubbers. It is also possible to employ solutions ofnatural or synthetic rubbers or rubber-like material in any suitablevehicle. The rubber'contains the usual -compounding and vulcanizingingredients, or a vulcanized rubber latex or rubber dispersion may beemployed, in which case the rubber layer does not require furthervulcanization.

When the backing employed is water soluble and the rubber constituent isa water dispersion of rubber orsimilar elastic material, it is essentialto protect the backing from the dispersion. and for this reason the sideof the backing which is to receive the rubber will receive a lightcoating which will give an interposed layer of a water resistantadhesive which will adhere to the backing layer and also to the rubber.A cement sultable for this purpose may be made from any of the wellknown rubber hydrochlorides. The material sold by du Pont under thetrade name RDL, the composition of which is maintained as a tradesecret, may also be employed. If some other vehicle or solvent for therubber is employed which will attack the backing layer. an appropriatechange in the composition of the intermediate adhesive will be made.

In certain forms of the'invention an insoluble or non-fugitive backingis employed. In such cases the backing material may be nylon" or one ofthe several polyvinyl chlorides, vinylidene chlorides, rubberhydrochloride or any other orientable film, and in the use of any ofthese materials, it is not necessary to interpose a layer of adhesive.

Having set forth the invention in general terms, practical applicationsthereof and means for making the same are shown in the accompanyingdrawings in which:

Fig. 1 is a diagrammatic showing of the rst several steps in a processin which a water soluble or other fugitive backing is employed and inwhich the rubber is applied as a water dispersion.

Fig. 2 shows the steps employed for the formation of the rubber threadwhen the backing material is elongated before the composite sheet is outinto threads.

Fig. 3 shows the twisting and covering of the thread on what is known asan up-twister.

Fig. iis a cross-section on the line 4-4 of Fig. 1 showing the sheetfrom which the threads are cut.

Fig. 5 is a view showing the thread separated into its constituentparts.

Fig. 6 is a view of an ordinary cross-woven fabric made from the thread,one of the threads being unraveled. In this view the fabric is deemed tohave been treated so as to remove the backing layer.

Fis. 7 is a cross-section of one modification of employed.

Flaneis aviewshowingafabricmadefrcmthe thread of I'lg. 7.

Fig. 9 shows a modldcation of the process after the sheet of backing andapplied rubber has been assembled.

Fig. 10 shows the second step in the liedied process.

Fig. 11 shows thetwisting and covering of threads, this view showing thestretching or elongation of the composite threads as taking placeconcurrently with the twisting and covering operations. In this view thethread is twisted and covered on a so-called down-twister."

Fig. 12 is a detail section on the line I-II of F18. 1l.

Referring to Fig. l, a sheet of polyvinyl alcohol or otler soluble orfugitive material is indicated at I asitispassedfromasupplyrollloveraguide roll 3 and thence to a pair of stretching rolls 4. The rolls 4 arepreferably driven at a substantially accelerated surface speed so as tostretch and partially orient the material, and to facilitate theelongation of the'material the roll 3 and the rolls 4, or either ofthem, may be gently heated to soften the backing sheet. While anysuitable degree .of stretching may be performed at this point, apolyvinyl alcohol sheet or film which can be elongated l000% before itsoomplete orientation, i. e.. when no further stretch can beimparted'thereto, will be elongated say 500% between the rolls 3 and 4.It is possible to omit all stretching during this stage in the vprocessand perform all of the stretchingof the backing at a later stage in theprocess.

From the rolls 4 the material in its partially stretched condition hasapplied to one side thereof a water-resistant adhesive l. The applicatorroll 1 indicates one means by which this operation may be performed.After the intermediate or protective layer is applied to the backing. itis ready to receive the coating or layer of rubber or similar elasticmaterial which is to form the body of the thread. In the drawing asimple form of spreader blade l is illustrated as merely A an example ofone means which may be used for l the purpose. -Behind this blade l is abank of elastic material in the form of latex or rubber dispersion whichis spread over the protective adhesive coating t'o a thicknessdetermined by the desired gauge or thickness of the nished rubberthread. In lieu of the spreading operation, the rubber may be applied byany suitable means, such, for example, as by caiendering.

From the rubber application point, the sheet of backing with itsoverlying rubber layer now passes into a. heated chamber Il where thelayer of rubber is dried and vulcanized. As the sheet, now carrying thevulcanized rubber layer, issues from the drier-vulcanizer it may receivea coating of soapstone or other material to render its surfacenon-adhesive. A dusting device for this purpose is indicated at Il. Thesheet is then rolled up as shown at l2 and the roll permitted to stand-until the material is cooled and sets.

A roll of the material i2 is then transferred to a location for the nextseries of steps. From the roll I2 the material is conducted to pairs ofstretching rolls I 5 and Il which may be heated and are driven atprogressively accelerated speeds to impart the final stretch andorientation to the backing material. This operation also stretches therubber to the desired degree. The distribution of the total elongationof the backing be- .5 y tween preliminary stretching rolls 3 and I andthe nal stretching rolls I5 and IB will beoptional, depending upon theamount of elongation required to bring the backing to complete orsubstantially complete orientation and also upon the degree of stretchor tension which it is desired to impart to the rubber. In lany event,the

amount of stretch which is imparted to the composite sheet between rollsI5 and i6 should be considerably under the elastic limit of the rubberso as to impart the light, easy or lazy tension t the rubber constituentof the thread in orderV the fact that the backing layer has been elonigated up to the point where little or no further elongation is possible,or, in the terms commonly used in this connection, the backing layer issaid to be fully oriented, i. e., the molecules have rearrangedthemselves so that no further elongation is possible. However, if thethread is relaxed, the rubber will tend to contract, throwing the threadinto a series of closely spaced spirals, but as the oriented backingcannot contract, the rubber will remain in longitudinal tension. Thethread will always assume a spiral formation with the backing layer onthe outside of the rubber.

This property of the composite thread to assume a natural twist orspiral is a substantial merit of the thread because the twisted orspiral rubber is under compression. A rubber thread made from such atwisted rubber core, has much superior aging qualities because thetwisted rubber is compressed laterally, although it is`sti1l underlongitudinal tension. The fact that the backing layer is on the outsidesurface of the thread will protect the thread from the air and reduce orretard oxidation. The surface of therubber which is next to the backingand at which point the rubber is under maximum tension is completelyshielded from the air.

It will be seen that as the thread as now constituted is firm and haslittle or no stretch or elongation because of the presence of theoriented backing layer, it may be used in any standard type of textilemachine with great ease and facility for the operator does not have tomake any allowances for stretch in the thread. It may be placed directlyin a loom or knitting machine if'bare rubber thread is to be used.However, it is generally preferred to cover a rubber thread with ajacket or winding of cotton, rayon, nylon or other textile materialbefore incorporating it in a garment.

For covering the material, the composite thread of rubber and backingmay be placed on the beam or spools of an ordinary covering machine andone or more layers of the textile material wrapped about it. Thecovering operation may be performed while the thread is held in straightor taut condition. It is preferred, however, to twist the rubber threadduring the covering.l operation so as to impart a certain degree ofadded elasticity to the thread. A device for this purpose is shown inFig. .3.

ard iup-twis covering machines. The package is rotated as shown and thecomposite thread passed 25, this operation imparting a twist to thethread. The amount of the-twist may exceed the natural twist, in lwhichcase the rubber will be placed under increased compression. This is anespecially valuable attribute of the invention, as rubber undercompression has much superior aging qualities. From the rolls 25 th'etwisted thread passes through the center of the rotating package 26which carries'one or more strands of the covering material which arewrapped in close covering spirals over the twisted thread which-nowbecomes the core of th'e covered elastic thread, now

indicated by the numeral 28. The outer wrapping maintains thecompression imparted to the rubber during the twisting operation. Itwill be observed that the direction of twists impartedby the `operationof the packages 22 and 26 are in opposition so that a substantiallybalanced or non-kinking thread is obtained, The thread thus obtainedh'as a certain degree of give or elasticity due to the fact that therubber and its backing layer are twisted in spiral form. The amount ofstretch of which this thread is capable is dependent upon the extent towhich the spirals of the backing material may straighten out. If averytight twist with a high order of twists per inch is imparted to thecomposite core at 22-24, the amount of elongation may be quite small,butif the twist is on a longer spiral with less twists per inch, thepossible elongation is greater. As the rubber is compressed within thespiral outer backing layer, there is always a point at which no furtherstretch can be imparted to the composite thread. 'I'he controllingfactor for the elongation is the oriented and non-stretchable backinglayer or ribbon which will give a total elongation only to the extent towhich the spirals of the backing may spread apart before they reachtheir limit. The rubber is still under a rather light tension when thecomposite thread has reached the limit of its extensibility.

What has, therefore, been accomplished is a thread shown in Fig. 5 whichhas exactly the same 'capacity for elongation as a highly tensionedrubber thread which may be used successfully and practically on standardelastic knitting, weaving or braiding machines. However, when thebacking is eliminated, as has been stated, the rubber constituent of thethread will contract and there is, therefore, obtainable a softlyyielding piece of elastic goods or fabric.

If, as suggested above, the twisting operation is omitted, the resultantcomposite thread will have a reduced elongation owing to the presence ofthe substantially non-stretchable backing, but when the backing iseliminated th'e latent tension in the rubber will be released and thethread will contract, giving a mild elasticity to the product. As therubber is not twisted in this form, the thread will not have as muchelasticity as in the preferred form.

In Fig. 6 is illustrated a simple. square woven fabric as an example ofthe product after the backing h'as been eliminated. This fabric will beconsidered to have been woven from threads 28 on an ordinary loom. Afterthe fabric was completed, it was given the usual water bath orscouringtreatment to remove dirt, oil, sizing and other extraneous matter andthe water has attacked the soluble backing i and that is now completelyeliminated. The material is an elastic fabric with through the wellknown flyer 24 to rolls a contractive property imparted by the tensionedand twisted rubber threads.

While for many types of fabrics it may be desirable or advantageous toremove the backing layer. in other fabrics this may not be so desirableand in that case any of the non-soluble, but orientable materials may beemployed.

In Fig. 7 the rubber layer or constituent is indicated at 9 and thebacking layer at l. In making this type of fabric or thread the sameprocedures are employed as in the one just described in full, exceptthat the protective adhesive 6 is not necessary. The degrees oi' stretchre- 'quired to give th'e preliminary and the ilnal orientation will bedetermined from the character of the material and the results desired,it being desirable always to impart an elongation after the applicationof the rubber layer which will give the desired tension to the rubberconstituent of the thread. As the backing is not eliminated, the amountof elasticity or stretch in this finished thread or fabric will bedetermined by the extent 8 celerated surface speed so that the compositema- 3 terial is given the stretch which is necessary to v rolls 44 andthe spindle the thread passes through to which the spirals o! thebacking layer may be elongated before the limit of extensibility isreached.

The process of manufacture shown in Figs. 9 to 12 diners from that shownand described hitherto mainly in the fact that the stretching of thecomposite material is performed afterit is cut into threads andsimultaneously with the twisting and covering or the threads.

In Fig. 9 a sheet of backing material and rubber is indicated at 30,this sheet having been made by the procedure illustrated in Fig. 1 or byany of the modiiled processes, The backing material may have been givena preliminary and partial stretch or it may be without any elongationlat this point. The material is ilrst cut into a series of tapes orrelatively wide ribbons by the slitting knives 32 and thence passed to apair of guide rolls 33 from which the ribbons or tapes are wound upon aplurality of storage spools 34. The rubber at this point is not underany tension whatever and the spools may be stored for av considerableperiod without deteriorationrof the rubber, and may be shipped to thethread maker in this condition.

For the manufacture of the finished thread a ribbon or tape is led fromthe roll 34 through a final slitter 35 where the composite material iscut into the narrow thread form, all of the threads being wound up on abeam indicated by the numeral 38. This beam is then mounted ina'covering machine.

The twisting and covering operation is performed in a. down twister andas shown diagrammatically in Fig. 11, it being understood that thedrawing is illustrative only and that the number of threads carried on abeam is limited only by the number of twisting units which may becarried on one twisting machine.

From the beam 36 each thread I8 is led to a pair of guide rolls 39 andthence to a group oi rolls by which the thread is stretched to completethe orientation of the backing and impart the desired tension to therubber element of .the composite thread. This group comprises a pair ofdrawing and guide rolls 40 and an intermediate roll 4I which may beheated moderately to facilitate the orientation of the backing.Preferably this roll 4i extends the entire length of a twisting unit.From roll 4| the thread passes to a second pair of rolls 42. The rolls40 and 4| are preterably driven at the same suri'ace speed as thedrawing rolls, but the rolls 42 are driven at an ac a spool or package4i containing the covering material 41 which passes through the ilyer Iland is wrapped about the thread, it being noted that the twists impartedbythe spindle 4I and the package 48 are in the reverse direction asindicated by the arrows. The covered thread passes through guide rolls50 and to a travelling eye or laye r\5| which winds Athe twisted andcovered thread upon the rotating spindle.

The method illustrated in Figs. 9 to 12 has certain advantages forcommercial practices. It is also advantageous because the order of theilnal thread slitting and stretching steps makes it possible to securemuch smaller gauge threads than is practical where the stretchingprecedes the final cutting operation.

For the manufacture of very fine rubber threads a. still furthervariation of the process may be employed. In such a case the backingmaterial is coated with a layer of unvulcanized rubber which is driedand then the composite sheet of backing material and unvulcanized rubberis stretched which orients the rubber and the backing sheetsimultaneously. While unvulcanized rubber will not orient uniformly, ifstretched by itself, the presence of the uniformly orientable backingwill cause the rubber to orient uniformly. This operation will give arubber film of extreme thinness. The composite sheet will then bevulcanized. If desired Ithe material may be given a fur-ther orientationafter vulcanization either in sheet form or after the sheet is cut intothreads. This will reduce the size of the threads still further.

It will be understood tha-t where the term rubber" is used, theintention is to cover any natural or synthetic rubber or elasticrubber-like material in any form.` By the term orientable is meant anyof the synthetic resins, vinyl compounds or any of the numerous plasticmaterials which have been developed in the arts which have the propertyof elongating to a denite or ilxed degree, a result which is commonlyattributed to an orientation of the molecules of the material. Thisproperty of stretching or orientation is frequently aided by theapplication of heat. By fugitive backing is meant a layer or sheet ofthis type oi' material which is soluble in a mediumwhich does not ailectthe elastic constituent or the covering material employed. Ordinarilythe fugitive material will be one which is water soluble so that it maybe readily removed by merely washing the thread or the completed fabricin a water bath, although other materials may be eliminated by othernon-deleterious treatments. It will also be appreciated that while it isdesirable to orient the backing partially so as to give a light degreeof tension to the rubber when the backing is fully oriented, this doesnot exclude performing all the orientation after the rubber layer isapplied. The orientation may be carried to the limit or it may approachthat degree. It will, therefore, be understood that the termorientation" or orienting is intended to cover both partial and completeorientation. Where the term threads is employed, it will be understoodto cover ilne and heavy threads, cords and cables, and "fabrics includeall types of textile material.

What is claimed is:

1. A laminated thread comprising a ilat ribbon of polyvinyl alcohol ina. condition of permanent elongation and orientation, and a lm of rubberadhering to a. surface of the ribbon and maintained in a state oflongitudinal tension by the ribbon.

2. A laminated thread comprising a flat ribbon of polyvinyl alcohol in acondition of permanent elongation and orientation, and a dried iilm ofrubber deposited from an aqueous dispersion thereof adhering to a iiatsurface of the ribbon. said rubber nlm being maintained in a state oflongitudinal tension by the ribbon.

3. A laminated thread comprising 9, llat ribbon of a water solublepolyvinyl resin in a condition of permanent elongation and orientation,a water resistant coating on a at surface of said ribbon, and a driedfilm of rubber deposited from an aqueous dispersion thereof adhering tothe coated surface of the ribbon and held in a state of longitudlnaltension by the ribbon.

4. .An elastic thread comprising a long narrow ribbon of polyvinylalcohol in a condition oi permanent elongation and orientation, and aillm of dried, vulcanized rubber deposited from an aqueous dispersion ofrubber on one surface of the ribbon, said rubber being in a dormantstate oi' tension in which i-t is held by the ribbon.

STERLING W. AIDERFER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

